Repairs to the South Road tram overpass in Black Forest were due to be completed in December, but now it looks like it will be weeks before the bridge reopens.

The bridge was built in 2010. Last January a beam shifted off its bearings, dropping debris onto the road below. Further investigation found structural damage and the bridge has been closed to cyclists and pedestrians ever since.

Now ABC News reports the repairs will stretch into February.

"Following the lifting of the structure to complete the planned repairs, additional works were identified that needed to be undertaken," said Transport Department spokesperson Paul Kermode.

The cost of the extra works will be covered by insurance.